LIVECONNECT - Some research I did couple of years ago, might be useful to share. This is gathered and not everything might work as it contains test cases I wrote, and snippets from other resources which maybe cannot be found elsewhere anymore.

Introduction
LiveConnect is a library that permits JavaScript and Java virtual machines to interoperate. Specifically, it enables JavaScript to access Java fields, invoke Java methods and enables Java to access JavaScript object properties and evaluate arbitrary JavaScript. LiveConnect was originally an integrated feature of both the Netscape Navigator browser and Netscape's server-side JavaScript. Now, it is a standalone library that can be embedded within other projects, such as the Mozilla browser.

I have to restate that LiveConnect is no longer with Mozilla, instead they hook it directly into a Java plugin. I'm not sure yet what is more dangerous,
because Java supports even more native features than LiveConnect did, they now rely on Java to get stuff done & secure.